PHP

Can anyone be so kind and explain me this bit of code?
$multipliers ="731";
$sum += $number{$i} * $multipliers{$i%3};

I can code PHP but dont know what {$i%3} means($i is a count value in a "for" ).

Thanks,
Marco

EDIT: A char combo caused an smiley...

Edited by fragenmensch 2005-11-05 9:00 AM

$i % 3 means "modulus of $i with divider 3" or something. Its the remainder after dividing $i by 3. Basically, you will get a value of 0~2, ie 0, 1, 2 depending on the value of $i.

eg,
$i = 10, $i%3 = 1
$i = 11, $i%3 = 2
$i = 12, $i%3 = 0 <== 12 is divisible by 3 giving remainder of 0

In the case of the code above, I believe uses the value returned in '$i%3' (0,1 or 2) to reference the characters in the string $multiplier, in this case "731". So

Value of $i Value of $i%3 Value of $multipliers{$i%3}
3 0 7
4 1 3
5 2 1

The fragment does not contain a definition of $number, but I presume it is defined somewhere above. And in this case, its value returned depends on $i itself.

PHP supports overloading of its variable-type that is extremely flexible. So the two numerical value of $number{$i} and $multipliers{$i%3} are multiplied together and added to $sum with the '+='

The statement
$sum += $number{$i} * $multipliers{$i%3};

basically expands to
$sum = $sum + $number{$i} * $multipliers{$i%3};

Hope this clarifies your queries.

EDIT: Rephrased for clarity in Italics

Edited by Snappy! 2005-11-06 5:38 AM

Yep, Snappy has it.

Basically $var{$x} means "the character at X index in the variable var".

Had to use this at work once... Hehe.

Thanks. This is a part of a checksum generator I found in the web, it creates vaild checksums for an german ID card and I want to port that from PHP to Perl, because a PHP Port to CE dosen't exist ATM.

Marco

PS: What do I need for doing this?